Power supply apparatus having plurality of planar fuel cell assemblies connected in stack form

ABSTRACT

A power supply apparatus comprising a plurality of planar fuel cell assemblies is disclosed. Each planar fuel cell assembly comprises two fuel cell members, a channel-forming member interposed between the two fuel cell members and defining a first channel for flowing a fluid fuel along with the two fuel cell members, and a coupling member to be coupled with an adjacent planar fuel cell assembly to define a second channel for flowing an ambient air, wherein the coupling member has a plurality of openings for flowing the ambient air therethrough.

FIELD OF THE INVENTION

The present invention relates to a power supply apparatus, and moreparticularly to a power supply apparatus including a plurality of planarfuel cell assemblies connected in a stack form.

BACKGROUND OF THE INVENTION

Fuel cells are well known and are commonly used to produce electricalenergy by means of electrochemical reactions. Comparing to theconventional power generation apparatus, fuel cells have advantages ofless pollutant, lower noise generated, increased energy density andhigher energy conversion efficiency. Fuel cells can be used in portableelectronic products, home-use or plant-use power generation systems,transportation, military equipment, the space industry, large-size powergeneration systems, etc.

According to the electrolytes used, fuel cells are typically classifiedinto several types, e.g. an alkaline fuel cell (AFC), a phosphoric acidfuel cell (PAFC), a molten carbonate fuel cell (MCFC), a solid oxidefuel cell (SOFC) and a proton exchange membrane fuel cell (PEMFC).Depending on types of the fuel cells, the operation principles aresomewhat different. For example, in the case of a direct methanol fuelcell (DMFC) which has the same structure as the PEMFC but uses liquidmethanol instead of hydrogen as a fuel source, methanol is supplied tothe anode, an oxidation reaction occurs in the presence of a catalyst,and protons, electrons and carbon dioxide are generated. The protonsreach the cathode through the proton exchange membrane. Meanwhile, inthe cathode, oxygen molecules take electrons from the anode and arereduced to oxygen ions by reduction. The oxygen ions react with hydrogenions from the anode and thus produce water.

As know, an individual fuel cell unit supplies limited voltage(approximately 0.4 V). For a purpose of offering a sufficient operatingvoltage to an electronic product, a plurality of fuel cell units shouldbe connected in series so as to form a fuel cell assembly. Depending onthe arrangement of the fuel cell units, the fuel cell assemblies can bedivided into two types, i.e. a stacked fuel cell assembly and a planarfuel cell assembly.

Referring to FIG. 1, an exploded view of a conventional stacked fuelcell assembly is illustrated. The stacked fuel cell assembly 10comprises at least two membrane-electrode assemblies (MEAs) 11, abipolar plate 12 located between two adjacent MEAs 11 and two electrodeplates 13 and 14 at opposite ends of the cell assembly. Each MEA 11includes an anode 111, a proton exchange membrane 112 and a cathode 113.The bipolar plate 12 comprises a plurality of channels 121 for flowingfuels and oxygen molecules therethrough. However, since the stacked fuelcell assembly 10 requires a large amount of cell units to be assembledin a stack form, the thickness and the weight thereof are considerablyhigh. Therefore, the usage of such stacked fuel cell assembly isrestricted in some situations.

Referring to FIG. 2, a planar fuel cell assembly 20 comprises a metalframe 21, a plurality of membrane-electrode assemblies (MEAs) 22 and twoelectrode plates 23 and 24 at opposite ends of the cell assembly.Likewise, each MEA 22 includes an anode, a proton exchange membrane anda cathode (not shown), and is embedded in the corresponding openings 211of the frame 21. Furthermore, two current collectors 212 are disposed atone side of the frame 21 as the current output terminals of the planarfuel cell assembly 20. Each of the electrode plates 23 and 24 compriseschannels 231 for flowing fuels and oxygen molecules therethrough.However, the metal frame 21 used in the planar fuel cell assembly 20 isboth bulky and weighty. In addition, the procedure of aligning the MEAs22 in the corresponding opening 211 of the frame 21 is complex andtime-consuming. Such planar fuel cell assembly 20 is costly tomanufacture, and also contribute a substantial weight and volume to theoverall fuel cell assembly. In other words, such planar fuel cellassembly fails to be used in portable electronic products.

SUMMARY OF THE INVENTION

The present invention provides a power supply apparatus including aplurality of planar fuel cell assemblies connected in a stack form, inwhich the power supply apparatus is easily assembled, suitable for massproduction and capable of offering a sufficient operating voltage

In accordance with the present invention, there is provided a powersupply apparatus comprising a plurality of planar fuel cell assemblies.Each planar fuel cell assembly comprises two fuel cell members, achannel-forming member interposed between the two fuel cell members anddefining a first channel for flowing a fluid fuel along with the twofuel cell members, and a coupling member to be coupled with an adjacentplanar fuel cell assembly to define a second channel for flowing anambient air, wherein the coupling member has a plurality of openings forflowing the ambient air therethrough.

In an embodiment, each of the two fuel cell members comprises aplurality of fuel cell units connected in series. Each fuel cell unitcomprises a meshed metal plate and a membrane-electrode assembly, themembrane-electrode assembly of each fuel cell unit having a first sidein contact with a second portion of the meshed metal plate and a secondside in contact with a first portion of the meshed metal plate of anadjacent fuel cell unit. The meshed metal plate of each fuel cell unitis made by punching or etching a plurality holes in a metal piece. Eachmembrane-electrode assembly includes an anode, a proton exchangemembrane and a cathode. The first portion and the second portion of themeshed metal plate are disposed at different levels by a gap.

In an embodiment, the channel-forming member further comprises a fuelinlet and a fuel outlet for introducing and discharging the fluid fuel,respectively.

In an embodiment, the power supply apparatus further comprises a fandisposed at a side thereof. Alternatively, the power supply apparatusfurther comprises a blower or an air pump for inhaling the ambient air,and a plurality of air-directing pipes in fluid communication with thesecond channel so as to gather and direct the ambient air.

In an embodiment, the coupling member comprises first and secondcoupling parts respectively disposed at outsides of the two fuel cellmembers.

In an embodiment, each of the first and second coupling parts comprisesseveral clasp sheets extending from an outer surface thereof to beengaged with ones of an adjacent planar fuel cell assembly.

In an embodiment, each of the first and second coupling parts comprisesseveral recess structures to be engaged with ones of an adjacent planarfuel cell assembly via an intermediate plate, and the intermediate platehas several protrudent rods at periphery thereof to be engaged withcorresponding cavities in each of the recess structures.

In an embodiment, the channel-forming member is integrally formed of aplastic material by an injection molding process.

In an embodiment, each planar fuel cell assembly further comprises acircuit connection member disposed at a bottom thereof to electricallyconnect with an adjacent planar fuel cell assembly, and the circuitconnection member comprises a first circuit connection portion disposedunder the second channel and a second circuit connection portiondisposed under the first channel. The first circuit connection portionhas at least one protrudent block on an edge thereof, and the secondcircuit connection portion has at least one depression structurecorresponding to the protrudent block.

The above contents of the present invention will become more readilyapparent to those ordinarily skilled in the art after reviewing thefollowing detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of a stacked fuel cell assembly according toprior art;

FIG. 2 is an exploded view of a planar fuel cell assembly according toprior art;

FIG. 3(A) is an exploded view illustrating a planar fuel cell assemblyof a power supply apparatus according to a preferred embodiment of thepresent invention;

FIG. 3(B) is a perspective view of the planar fuel cell assembly in FIG.3(A);

FIG. 4(A) is an exploded view of a fuel cell unit;

FIG. 4(B) is an exploded view illustrating a plurality of fuel cellunits of FIG. 4(A) connected in series and coupled to thechannel-forming member;

FIG. 5 is a perspective view of a power supply apparatus according to afirst preferred embodiment of the present invention;

FIG. 6 is a perspective view of a power supply apparatus according to asecond preferred embodiment of the present invention;

FIG. 7 is a perspective view of a power supply apparatus according to athird preferred embodiment of the present invention;

FIG. 8 is a perspective view of a power supply apparatus according to afourth preferred embodiment of the present invention;

FIG. 9(A) is an exploded view of a power supply apparatus according to afifth preferred embodiment of the present invention;

FIG. 9(B) is a perspective view of the power supply apparatus in FIG.9(A);

FIG. 10 is a perspective view of a power supply apparatus according to asixth preferred embodiment of the present invention; and

FIGS. 11(A), 11(B) and 11(C) are schematic views illustrating thecircuit connection configuration of adjacent planar fuel cellassemblies.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically withreference to the following embodiments. It is to be noted that thefollowing descriptions of preferred embodiments of this invention arepresented herein for purpose of illustration and description only. It isnot intended to be exhaustive or to be limited to the precise formdisclosed.

Referring to FIGS. 3(A) and 3(B), a planar fuel cell assembly of a powersupply apparatus according to a preferred embodiment of the presentinvention is shown. In this embodiment, the planar fuel cell assembly 3comprises two fuel cell members 31, a channel-forming member 32 and acoupling member 33. The channel-forming member is disposed between thesetwo fuel cell members 31. The coupling member 33 comprises a firstcoupling part 331 and a second coupling part 332, which are respectivelydisposed at the outsides of the two fuel cell members 31. The firstcoupling part 331 and the second coupling part 332 have many openings333 such that the surfaces of these two fuel cell members 31 are exposedto the ambient air. In addition, several clasp sheets 334 extend fromthe outer surfaces of the first coupling part 331 and the secondcoupling part 332. The number of clasp sheets 334 on the first couplingpart 331 is equal to that on the second coupling part 332. The clasp ofthe clasp sheet 334 on the first coupling part 331 of this planar fuelcell assembly 3 will be engaged with the corresponding one on the secondcoupling part 332 of an adjacent planar fuel cell assembly (not shown).Whereas, the clasp of the clasp sheet 334 on the second coupling part332 of this planar fuel cell assembly 3 will be engaged with thecorresponding one on the first coupling part 331 of another adjacentplanar fuel cell assembly (not shown). The channel-forming member 32comprises a hollow portion 321 enclosed by the protrudent edges 320thereof. Several raised rods 322 are extended from two opposite edgestoward the hollow portion 321. The raised rods 322, along with the twofuel cell members 31 and the protrudent edges 320, define a channel 323for flowing a fluid fuel therethrough. The channel-forming member 32 isfurther provided with a fuel inlet 324 and a fuel outlet 326 forintroducing and discharging the fluid fuel, respectively. There are manysupporting blocks 325 disposed beside the protrudent edges 320 and theraised rods 322 for supporting the fuel cell units 31.

Referring to FIG. 4(A), a fuel cell unit 41 constituting an individualfuel cell member 31 of FIG. 3 is shown. In this embodiment, the fuelcell unit 41 comprises a meshed metal plate 411 and a membrane-electrodeassembly (MEA) 412. The meshed metal plate of each fuel cell unit ismade by punching or etching a plurality holes in a metal piece. Themeshed metal plate 411 comprises a first portion 4111 and a secondportion 4112 disposed at different levels by a gap of “d”. The MEA 412is disposed on the second portion 4112, and includes an anode, a protonexchange membrane and a cathode (not shown). The first side 4121 of theMEA 412 is in contact with the top surface 41121 of the second portion4112. For a purpose of offering a sufficient operating voltage to anelectronic product, several fuel cell units 41 of FIG. 4(A) should beconnected in series and supported on the supporting blocks 325 of thechannel-forming member 32 so as to form the fuel cell member 31, as isshown in FIG. 4(B). Likewise, the identical number of fuel cell units 41are connected in series and mounted on the opposite side of thechannel-forming member 32. The resultant structure is then covered withthe coupling member 33 to form the planar fuel cell assembly 3 of FIG.3.

Take a direct methanol fuel cell (DMFC) for example. During operation ofsuch planar fuel cell assembly 3, methanol is supplied into the channel323 of the channel-forming member 32 via the fuel inlet 324. In theanode, an oxidation reaction occurs in the presence of a catalyst, andthus protons, electrons and carbon dioxide are generated. The protonsreach the cathode through the proton exchange membrane to the cathode.The oxygen molecules containing in the air will flow through the meshedmetal plate of the individual fuel cell unit to the cathode. Meanwhile,in the cathode, oxygen molecules take electrons from the anode and arereduced to oxygen ions by reduction. The oxygen ions react with hydrogenions from the anode and thus produce water.

For a purpose of offering a sufficient operating voltage to anelectronic product, a plurality of planar fuel cell assemblies 3 shownin FIG. 3(B) should be connected in a stack form. Referring to FIG. 5,every planar fuel cell assembly 3 is coupled with adjacent one via theclasp sheets 334 thereon so as to result in a power supply apparatus 5.The clasp of the clasp sheet 334 on the first coupling part 331 of anyplanar fuel cell assembly 3 will be engaged with the corresponding oneon the second coupling part 332 of an adjacent planar fuel cell assembly(not shown). Whereas, the clasp of the clasp sheet 334 on the secondcoupling part 332 will be engaged with the corresponding one on thefirst coupling part 331 of another adjacent planar fuel cell assembly(not shown). After the engagement of two adjacent planar fuel cellassemblies 3, an airflow channel 51 is defined between the firstcoupling part 331 of one planar fuel cell assembly and the secondcoupling part 332 of the other planar fuel cell assembly. In addition tothe airflow channel 51, the openings 333 of the first coupling part 331and the second coupling part 332 will allow the ambient air to flowthrough the meshed metal plate of the individual fuel cell unit to thecathode. For a purpose of enhancing amount of the supplied oxygenmolecules and thus increasing the reaction in the cathode, a fan 52 isprovided at one side of the power supply apparatus 5.

In the above embodiments, the clasps of clasp sheets 334 on the firstcoupling part 331 are somewhat different from those on the secondcoupling part 332. Therefore, the first coupling part 331 and the secondcoupling part 332 should be separately fabricated. In order to reducethe fabricating complexity, the first coupling part 331 and the secondcoupling part 332 can be made identical. In other words, the couplingmember 33 may be modified.

A further embodiment of a power supply apparatus is illustrated in FIG.6. In this embodiment, the fuel cell members and the channel-formingmember included therein are similar to those shown in FIG. 5, and arenot to be redundantly described herein. However, the coupling member 33further comprises several intermediate plates 61, and the clasp sheets334 on the first coupling part 331 and on the second coupling part 332are replaced by recess structures 335. By the engagement of theintermediate plates 61 with the recess structures 335 of two adjacentplanar fuel cell assemblies, the power supply apparatus 6 is assembled.

A further embodiment of a power supply apparatus is illustrated in FIG.7. In this embodiment, the intermediate plates 61 of the coupling member33 included therein are similar to those shown in FIG. 6. However,widths of the first coupling part 331 and the second coupling part 332are as short as possible so as to reduce the overall volume of the powersupply apparatus 7.

A further embodiment of a power supply apparatus is illustrated in FIG.8. In this embodiment, the periphery of the intermediate plate 61 hasseveral protrudent rods 63. At the locations corresponding to theprotrudent rods 63, the recess structures 335 of the first coupling part331 and on the second coupling part 332 further comprise severalcavities 62. By the engagement of the protrudent rods 63 with thecavities 62 of two adjacent planar fuel cell assemblies, the powersupply apparatus 8 is assembled.

A further embodiment of a power supply apparatus is illustrated in FIGS.9(A) and 9(B). In this embodiment, the fuel cell members and thechannel-forming member included therein are similar to those shown inFIG. 5, and are not to be redundantly described herein. However, the fan52 can be replaced with a blower 72, or an air pump (not shown). Via theblower 72 or the air pump, the ambient air will be inhaled into thepower supply apparatus. In addition, several air-directing pipes 73 arein fluid communication with the airflow channels 51 between two adjacentplanar fuel cell assemblies. The ambient air passing through the airflowchannels 51 will be gathered together and directed by the air-directingpipe 73 in a specified direction. Therefore, the reaction efficiency inthe cathode is largely increased.

In the above embodiments, the engagement of the recess structure withthe intermediate plate or the engagement of the protrudent rod with thecavity is presented herein for purpose of illustration and descriptiononly. The shape, size or number of the coupling member is not limited tothe precise form disclosed. In addition, the size of the channel-formingmember preferably conforms to the width of each planar fuel cellassembly. Preferably, the channel-forming member is integrally formed ofa plastic material by an injection molding process. Certainly, thechannel-forming member can also be formed of a material other thanplastic, such as metal.

Moreover, the power supply apparatus of the present invention furthercomprises a circuit connection member. Referring to FIG. 10, the circuitconnection member 80 is disposed at the bottom (or top) of the powersupply apparatus and comprises a first circuit connection portion 81 anda second circuit connection portion 82. The first circuit connectionportion 81 is disposed under the airflow channels 51 between twoadjacent planar fuel cell assemblies and has several protrudent blocks811 on the edges thereof. The second circuit connection portion 82 isdisposed under the channel-forming member 32 and has depressionstructures 821 engaged with the protrudent blocks 811 of an adjacentfirst circuit connection portion 81. The protrudent blocks 811 and thedepression structures 821 have conductive surfaces. Via the circuitconnection member 80, every two adjacent planar fuel cell assemblies canbe electrically connected with each other in series or in parallel. Asshown in FIG. 11(A), the internal circuits of the first circuitconnection portion 81 and the second circuit connection portion 82 arearranged such that the positive electrodes thereof are electricallyconnected to the negative electrodes. In such manner, every two adjacentplanar fuel cell assemblies can be electrically connected with eachother in series. Alternatively, in FIG. 11(B), the internal circuits ofthe first circuit connection portion 81 and the second circuitconnection portion 82 are arranged such that the like electrodes thereofare electrically connected to the like electrodes. Therefore, every twoadjacent planar fuel cell assemblies can be electrically connected witheach other in parallel. Furthermore, in order to simplify thefabricating process, these circuit connection portions can haveidentical structures. For example, as shown in FIG. 11(C), each of thefirst circuit connection portion 81 and the second circuit connectionportion 82 has a protrudent block 811 on a side thereof and a depressionstructure 821 on the opposite side thereof. Via the engagement of theprotrudent block 811 with the depression structure 821, every twoadjacent planar fuel cell assemblies can be electrically connected witheach other in series.

From the above description, the power supply apparatus of the presentinvention is stacked by a plurality of planar fuel cell assemblies. Thearrangement of the fan or blower facilitates enhancing amount of thesupplied oxygen molecules and thus increasing the reaction in thecathode. Since every two adjacent planar fuel cell assemblies can beelectrically connected with each other in series, this power supplyapparatus can offer more sufficient operating voltage as required.Alternatively, the pot life of the power supply apparatus can beincreased when every two adjacent planar fuel cell assemblies areelectrically connected with each other in parallel. Since the bulkymetal frame and the bipolar plate used in the conventional planar fuelcell assembly are omitted, the overall weight of the present planar fuelcell assembly is reduced.

While the invention has been described in terms of what is presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the invention needs not be limited to the disclosedembodiment. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

1. A power supply apparatus comprising a plurality of planar fuel cellassemblies, each planar fuel cell assembly comprising two fuel cellmembers, a channel-forming member interposed between said two fuel cellmembers and defining a first channel for flowing a fluid fuel along withsaid two fuel cell members, and a coupling member to be coupled with anadjacent planar fuel cell assembly to define a second channel forflowing ambient air, wherein said coupling member has a plurality ofopenings for flowing ambient air therethrough.
 2. The power supplyapparatus according to claim 1 wherein each of said two fuel cellmembers comprises a plurality of fuel cell units connected in series. 3.The power supply apparatus according to claim 2 wherein each fuel cellunit comprises a meshed metal plate and a membrane-electrode assembly,said membrane-electrode assembly of each fuel cell unit having a firstside in contact with a second portion of said meshed metal plate and asecond side in contact with a first portion of said meshed metal plateof an adjacent fuel cell unit.
 4. The power supply apparatus accordingto claim 3 wherein said meshed metal plate of each fuel cell unit ismade by punching a plurality of holes in a metal piece.
 5. The powersupply apparatus according to claim 3 wherein said meshed metal plate ofeach fuel cell unit is made by etching a plurality of holes in a metalpiece.
 6. The power supply apparatus according to claim 3 wherein eachmembrane-electrode assembly includes an anode, a proton exchangemembrane and a cathode.
 7. The power supply apparatus according to claim3 wherein said first portion and said second portion of said meshedmetal plate are disposed at different levels by a gap.
 8. The powersupply apparatus according to claim 1 wherein said channel-formingmember further comprises a fuel inlet and a fuel outlet for introducingand discharging said fluid fuel, respectively.
 9. The power supplyapparatus according to claim 1 further comprising a fan disposed at aside thereof.
 10. The power supply apparatus according to claim 1further comprising: a blower for inhaling ambient air; and a pluralityof air-directing pipes in fluid communication with said second channelso as to gather and direct ambient air.
 11. The power supply apparatusaccording to claim 1 further comprising: an air pump for inhalingambient air; and a plurality of air-directing pipes in fluidcommunication with said second channel so as to gather and directambient air.
 12. The power supply apparatus according to claim 1 whereinsaid coupling member comprises first and second coupling partsrespectively disposed at outsides of said two fuel cell members.
 13. Thepower supply apparatus according to claim 12 wherein each of said firstand second coupling parts comprises several clasp sheets extending froman outer surface thereof to be engaged with ones of an adjacent planarfuel cell assembly.
 14. The power supply apparatus according to claim 12wherein each of said first and second coupling parts comprises severalrecess structures to be engaged with ones of an adjacent planar fuelcell assembly via an intermediate plate.
 15. The power supply apparatusaccording to claim 14 wherein said intermediate plate has severalprotrudent rods at a periphery thereof to be engaged with correspondingcavities in each of said recess structures.
 16. The power supplyapparatus according to claim 1 wherein said channel-forming member isintegrally formed of a plastic material by an injection molding process.17. The power supply apparatus according to claim 1 wherein each planarfuel cell assembly further comprises a circuit connection memberdisposed at a bottom thereof to electrically connect with an adjacentplanar fuel cell assembly.
 18. The power supply apparatus according toclaim 17 wherein said circuit connection member comprises a firstcircuit connection portion disposed under said second channel and asecond circuit connection portion disposed under said first channel. 19.The power supply apparatus according to claim 18 wherein said firstcircuit connection portion has at least one protrudent block on an edgethereof, and said second circuit connection portion has at least onedepression structure corresponding to said protrudent block.